Not Applicable
Not Applicable
1. Field of the Invention
This invention relates to a cross-connect switch for fiber-optic communication networks including wavelength division multiplexed (WDM) networks, and more particularly to such an optical switch using a matrix of individually tiltable micro-mirrors.
2. Description of the Background Art
Multi-port, multi-wavelength cross-connect optical switches with characteristics of large cross-talk rejection and flat passband response have been desired for use in wavelength-division multiplexed (WDM) networks. Four-port multi-wavelength cross-bar switches based on the acousto-optic tunable filter have been described (xe2x80x9cIntegrated Acoustically-tuned Optical Filters for Filtering and Switching Applications,xe2x80x9d D. A. Smith, et al., IEEE Ultrasonics Symposium Proceedings, IEEE, New York, 1991, pp. 547-558), but they presently suffer from certain fundamental limitations including poor cross-talk rejection and an inability to be easily scaled to a larger number of ports. Attempts are being made to address to this problem by dilating the switch fabric, both in wavelength and in switch number, to provide improved cross-talk rejection and to expand the number of switched ports so as to provide an add-drop capability to the 2xc3x972 switch fabric. This strategy, however, adds to switch complexity and cost. Recently, Patel and Silberberg disclosed a device employing compactly packaged, free-space optical paths that admit multiple WDM channels spatially differentiated by gratings and lenses (xe2x80x9cLiquid Crystal and Grating-Based Multiple-Wavelength Cross-Connect Switch,xe2x80x9d IEEE Photonics Technology Letters, Vol. 7, pp. 514-516, 1995). This device, however, is limited to four (2xc3x972) ports since it relies on the two-state nature of polarized light.
It is therefore an object of this invention to provide an improved multi-wavelength cross-connect optical switch which is scalable in port number beyond 2xc3x972.
Another object of the invention to provide such an optical switch which can be produced by known technology.
Another object of this invention to provide such an optical switch with high performance characteristics such as basic low loss, high cross-talk rejection and flat passband characteristics.
Another object of the invention is to provide a fiber-optic switch using two arrays of actuated mirrors to switch or rearrange signals from N input fibers onto N output fibers, where the number of fibers, N, can be two, or substantially larger than 2.
Another object of the invention is to provide a fiber-optic switch using 1-D arrays of actuated mirrors.
Another object of the invention is to provide a fiber-optic switch using 2-D arrays of actuated mirrors.
Another object of the invention is to provide a fiber-optic switch using mirror arrays (1-D or 2-D) fabricated using micromachining technology.
Another object of the invention is to provide a fiber-optic switch using mirror arrays (1-D or 2-D) fabricated using polysilicon surface micromachining technology.
Another object of the invention is to provide a fiber-optic switch using arrays (1-D or 2-D) of micromirrors suspended by torsion bars and fabricated using polysilicon surface micromachining technology.
Another object of the invention is to provide a fiber-optic switch with no lens or other beam forming or imaging optical device or system between the mirror arrays.
Another object of the invention is to provide a fiber-optic switch using macroscopic optical elements to image or position the optical beams from the input fibers onto the mirror arrays, and likewise using macroscopic optical elements to image or position the optical beams from the mirror arrays onto the output fibers.
Another object of the invention is to provide a fiber-optic switch using microoptics to image or position the optical beams from the input fibers onto the mirror arrays, and likewise using microoptics to image or position the optical beams from the mirror arrays onto the output fibers.
Another object of the invention is to provide a fiber-optic switch using a combination of macrooptics and microoptics to image or position the optical beams from the input fibers onto the mirror arrays, and likewise using combination of macrooptics and microoptics to image or position the optical beams from the mirror arrays onto the output fibers.
Another object of invention is to provide a fiber-optic switch in which the components (fibers, gratings, lenses and mirror arrays) are combined or integrated to a working switch using Silicon-Optical-Bench technology.
Another object of the invention is to provide a fiber-optic switch using 2-D arrays of actuated mirrors and dispersive elements to switch or rearrange signals from N input fibers onto N output fibers in such a fashion that the separate wavelength channels on each input fiber are switched independently.
Another object of the invention is to provide a fiber-optic switch as described above, using diffraction gratings as wavelength dispersive elements.
Another object of the invention is to provide a fiber-optic switch as described above, using micromachined diffraction gratings as wavelength dispersive elements.
Another object of the invention is to provide a fiber-optic switch using fiber Bragg gratings as wavelength dispersive elements.
Another object of the invention is to provide a fiber-optic switch using prisms as wavelength dispersive elements.
Another object of the invention is to provide a fiber-optic based MEMS switched spectrometer that does not require mechanical motion of bulk components nor large diode arrays, with readout capability for WDM network diagnosis.
Another object of the invention is to provide a fiber-optic based MEMS switched spectrometer that does not require mechanical motion of bulk components nor large diode arrays, with readout capability for general purpose spectroscopic applications.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.
An optical switch embodying this invention, with which the above and other objects can be accomplished, may be characterized as comprising a wavelength dispersive element, such as a grating, and a stack of regular (non-wavelength selective) cross bar switches using a pair of two-dimensional arrays of micromachined, electrically actuated, controlled deflection micro-mirrors for providing multiport switching capability for a plurality of wavelengths.